The University of Pennsylvania (UPENN) and Children's Hospital of Philadelphia (CHOP) have had an NHLBI- sponsored T32 training grant for the support of pre- and post-doctoral trainees for the past 9 years in the inter- related areas of hemostasis, thrombosis and vascular biology. These areas have great clinical importance as heart attacks and strokes remain the number one cause of mortality in our industrial society. Many other diseases from deep vein thrombosis to heparin-induced thrombocytopenia to even Sickle Cell Disease are of strong clinical importance and involve hemostatic/thrombotic dysfunction. Yet in spite of these pressing clinical needs, potential trainees are drawn instead into the parallel fields of cancer research or cardiology. We believe that we have developed a successful competitive program in part because the research faculty and opportunities on the UPENN/CHOP campus in hemostasis/ thrombosis/vascular biology is highly productive, interactive and committed to mentoring the next generation of investigators. This rich environment, plus what we believe is a very well-designed and implemented T32 vision, has allowed us to attract strong pre- and postdoctoral trainees over the past 9 years. In the coming 5 years of support, we propose to retain the same number of trainees, but further strengthen the program by the following 3 changes: 1) a weekly journal club in hemostasis and thrombosis by two of our participating faculty members that had been informally attended by the trainees will now become mandatory. 2) A one week course intensive clinical coagulation laboratory course will be required of all of our trainees to give even our PhD trainees a visual image and comfort in the clinical tests that are done at a major tertiary hospital in the evaluation and care of patients with hemostatic/thrombotic disorders. 3) We have invited a former UPENN faculty member, who had trained with the T32's Director and is now a leader in clinical trials in hemostatic disorders in the pharmaceutical field, to participate as an external reviewer. He will provide important insights and guidance to our trainees as many of them will transition from academia with a focus on basic research to more translational and clinical research in private industry. Thus, we believe that we are an outstanding training program with an extra-ordinarily rich and interactive group of faculty members that has provided important research opportunities along with a concurrent strong didactic program and mentoring and that we will continue to train individuals who will make important contributions to our research field.